This invention concerns an improved free-wheel mechanism for bicycles, in particular improvements in the adjustment system of such a mechanism.
It is known that the free-wheels to be asembled on the rear driving wheel of bicycles are mechanisms comprising an inner body integral with the wheel hub and an outer body carrying the chain drive sprockets of the bicycle, pedal-driven, said outer body being assembled rolling on the inner body through two sets of balls, positioned circumferentially, housed in suitable seats of the two bodies. It is also known that, for good operation of the free-wheels, it is very important to be able to adjust the position of the outer body with respect to the inner one in the simplest, most precise way, in both the longitudinal direction of the wheel axxis, and in the centering direction with respect to this axis.
The means of adjustment normally used consist of some flat-faced spacing rings of various thicknesses, placed between the flat-faced head of an adjustment "cone"--which forms part of the seat of one of the sets of balls, and which is screwed on the inner body of the free-wheel--and a shoulder, also flat-faced, obtained on said inner body and projecting from the same.
As this type of assembly permits an adjustment practically only in the axial direction, its precision, as regards the centering of the parts on the axis of rotation, is rather unsatisfactory. Working imprecisions, in fact, come into play e.g. the faults of parallelism between the faces of the spacers, the lack of squareness of the opposite faces of the cone and shoulder with the axis of the device and the lack of coupling precision of the threading of the cone with that of the inner body, which do not permit that precise centering that is desirable between the parts.
The purpose of this invention is to eliminate these drawbacks and to provide a free-wheel, with easy and at the same time, very precise adjustment, in both the axial and the centering direction with substantial improvements in the quality of the device compared to those of the prior art.